Vascular reactivity of rats altered by cadmium and a zinc chelate

Chronic arterial hypertension is induced in rats by feeding or injecting cadmium. To ascertain if reactivity of blood vessels in such rats was altered, the vascular responses to intravenously injected norepinephrine and angiotensin were studied. Rats, fed 10 ppm of cadmium in water for two to four months, had higher pressures than rats on a low cadmium regimen, but had depressed responses to norepinephrine and angiotensin. Cadmium, intraperitoneally injected in normal rats, caused immediate elevations of blood pressure in 11 of 15 cases. Injection of a chelate of zinc (Na ₂ Zn CDTA) resulted in lower pressures in control and cadmium-fed animals, and restoration of vascular responses to norepinephrine, when corrected by regression analysis to normal pressure levels. Cadmium hypertension may be accompanied by diminished vascular reactivity, as with some types of human hypertension.